Written By Gopal Krishna on Sunday, May 16, 2010 | 12:23 AM

It actually costs more to generate electricity at a waste-to-energy plant than it does at a coal, nuclear, or hydropower plant.

Waste-To-Energy: Energy from Garbage

Garbage, often called municipal solid waste (MSW), is the source of about 10% of the total biomass energy consumed in the United States. MSW contains biomass (or biogenic) materials like paper, cardboard, food scraps, grass clippings, leaves, wood, and leather products, and other non-biomass combustible materials, mainly plastics and other synthetic materials made from petroleum.

Pie chart showing percent of MSW landfilled or burned, 2007. Paper/paperboard 22% or 37.8 million tons; food 18% or 30.9 million tons; plastics 17% or 28.6 million tons; glass/metal/misc. inorganic 16% or 27.7 million tons; wood 8% or 12.9 million tons; yard trimmings 7% or 11.7 million tons; textiles 6% or 10.0 million tons; rubber and leather 4% or 6.4 million tons; other 2% or 3.3 million tons.

A pie chart with percentages showing what we do with trash in the United States. Landfill 55%; Recycle 31%; Burn 14%. Source the NEED Project.

Source: The National Energy Education Project (Public Domain)

Since 1985, recycling and composting programs in the United States have reduced the share of biogenic material in MSW that is land filled or burned, while the share of non-biogenic content has increased. About 60% of the MSW (by weight) that is now land filled or burned is biogenic. The biogenic material contributes about 55% of the energy when MSW is burned in waste-to-energy facilities. Decomposing biomass in MSW landfills produces methane, which is captured and used to generate electricity at many large landfills.

Americans produce more and more waste each year. In 1960, the average American threw away 2.7 pounds of trash a day. Today, each American throws away about 4.5 pounds of trash every day. What are we going to do with all our trash? One solution is to burn it. (Burning is sometimes called combustion.) Organic waste is waste that is made from plant or animal products. All organic waste contains energy. People have burned one type of organic material — wood — for hundreds of thousands of years. Ancient peoples burned wood to keep themselves warm and to cook their food.

Waste-to-Energy Plants Make Steam and Electricity

Today, we can burn garbage in special waste-to-energy plants and use its heat energy to make steam to heat buildings or to generate electricity. There are about 90 waste-to-energy plants in the United States. These plants generate enough electricity to supply almost 3 million households.Waste-to-Energy Plants Also Dispose of Waste

But providing electricity is not the major advantage of waste-to-energy plants. It actually costs more to generate electricity at a waste-to-energy plant than it does at a coal, nuclear, or hydropower plant.

The major advantage of burning waste is that it reduces the amount of garbage we bury in landfills. Waste-to-energy plants dispose of the waste of 40 million people.

The average American produces more than 1,600 pounds of waste a year. If all this waste were landfilled, it would take more than two cubic yards of landfill space. That's the volume of a box 3 feet long, 3 feet wide, and 6 feet high. If that waste were burned, the ash residue would fit into a box 3 feet long, 3 feet wide, but only 9 inches high.

Solid Waste Incinerators Simply Dispose of Waste

There also are solid waste incinerators that simply burn trash. They don't use the heat energy to make steam or electricity.

Between waste-to-energy plants and solid waste incinerators, the United States burns 14% of its solid waste.